GREENSBORO — The student at Southern Elementary who was found to have MRSA was the second student in Guilford County Schools to get the staph infection this school year.

The other case was in December, although school officials could not recall at which school.

MRSA, officially known as methicillin-resistant staphylococcus aureus, is a staph infection that is resistant to certain anti­biotics, such as methicillin and penicillin, which makes it harder to treat.

School officials are not releasing the grade or age of the boy who received the diagnosis of MRSA on Tuesday because they don’t want to identify him, said Leonard Simpson of Guilford County Schools.

However, the student has been treated by a doctor and can return to school.

It’s not known how this student contracted the infection, but MRSA is most commonly transmitted through open cuts or wounds, shared equipment, poor hygiene, razors, or breathing tubes and medical equipment.

It may be difficult to tell how someone contracts a staph infection, said Ward Robinson, medical director of the Guilford County Department of Public Health.

“The source may not have symptoms,” Robinson said. “There is also some literature linking (MRSA) transmission to food sources.”

MRSA also is something that comes and goes in spurts.

“MRSA has been sporadic for years,” Robinson said.

“Cases appear in the community without warning or explanation,” he said. “However, its presence in our region has been noted for years, and this case is neither unusual nor a surprise.”

Southern Elementary sent a letter to parents alerting them to the situation. The letter told parents the infected student’s classroom was disinfected on Wednesday.

Robinson said parents don’t need to be too worried about their children getting MRSA just from touching a table or chair that the student who had the infection may have touched.

“Environment is not considered to be a significant contributor to transmission of staph infection,” he said. “It’s human-to-human or food-to-human transmission. Cleaning classrooms after a case is commonly done but doesn’t help reduce transmission.”

He did say the school’s custodian used antimicrobial disinfectant solution to wipe down all hard surfaces as a precaution.